Not tech, but I'm willing to bet it's geeky enough to go here.
Been collecting fossilized shark teeth for well over a decade now. My pride and joy is a 4 inch Carcharocles megalodon lateral, but I've got a lot of these things!
My main collection (as of a year or two ago, anyway). The prized meg is that big tooth is that massive one in the bottom left corner. There's a few shell fossils as well, as well as some fake arrowheads my mom found in Iowa (the fossil hunting trail that she found them in was apparently seeded with these things. She was a tad upset when she found out they weren't real, given she walked quarter mile with a cane to find this stuff and has paraparesis).
My "Junk teeth." The large serrated tooth on the bottom right was given to a relative. This image is also outdated because the teeth are now organized.
Two shark teeth I got a year or so ago, a Galeocerdo contortus and a Galeocerdo mayumbensis. Both are extinct tiger sharks (although the contortus is debatable).
My megatooth shark teeth (right two rows) and great white teeth (left two rows.) Some of the great white teeth belong to a species called
Cosmopolitodus hastalis--these would be the ones on the far left, with a transitional tooth at the top. C. hastalis is considered to be the direct ancestor of the modern great white, and many of the broad form teeth are indistinguishable from modern white shark teeth that have worn serrations. The transitional tooth was misidentified as a species known as C. escheri when I bought it, but that species is only found in an isolated area in Eastern Europe and was a dead end; this tooth is instead a partly serrated C. hastalis tooth from Chile, which is where the great white is thought to have first evolved. Penny for size reference.
Palaeocarcharodon orientalis. Once thought by some scientists as the ancestor of both the great white and megalodon, it's now considered to be a dead end. This is the second one I owned (the one in the junk teeth pic was the first), but the first was broken by a careless relative. Shame too, as it was a huge tooth in good condition. I have some of its relatives in my main collection.
Got this thing for Christmas! A non-repaired Otodus obliquus tooth (megalodon ancestor) in matrix. I have three other Otodus teeth, but they were all bought repaired at a shady local rock shop. Wouldn't be the last time I was ripped off by them, either.
Reverse side of the Christmas gift. That's a Cretolamna appendiculata tooth you see at the top--they can only be distinguished from its descendant (Otodus) by size and thickness of the tooth (the latter is handy when you have a juvenile Otodus tooth). C. appendiculata to megalodon are considered by some to be a chronospecies--a single species evolving over years (in this case, a more than 63 million year time span). The same can likely be said of C. hastalis and the modern great white. There's also a broken shark tooth--likely a Scapanorhynchus texanus (possibly goblin shark from that era), but it's hard to see--look on the bottom left of the matrix.
The Christmas fossil was purchased from a dealer (a reliable one I've been user for years--there are few shark teeth in my area, due to me living in an area that is geologically Paleozoic and sparce in outcroppings), who found it themselves and accidentally fractured the third tooth preparing it for exhibit. They dug into their private collection to sell it, actually.
